Field
The following invention disclosure is generally concerned with wearable electronic instruments and specifically concerned with watch type timepieces which incorporate a heart rate function and the fit of these devices on the human wrist.
A timepiece commonly known as a wrist watch is small in size and arranged to be affixed and worn about the human wrist. Some technically advanced timepieces incorporate mechanisms which allow one to monitor heart rate. Optical sensors probe the tissue of the wearer and may be used to detect the pulse and pulse rate. Thus, ones heart rate may be made available to the wearer via a numeric display on the face of the watch. Some examples of heart rate monitors which may be built into wristwatches include:
A reflection type oximeter taught by Takatani et al, in U.S. Pat. No. 4,867,557 uses changes in light pulses which are variably absorbed by blood oxygen.
Inventor Tan et al has combined a special apparatus which accommodates a finger therein and provides for optical probing of tissue via a light source and detector which are strongly coupled to tissue in U.S. Pat. No. 4,825,872.
Cramer et al teaches of a wrist borne pulse meter and chronometer in U.S. Pat. No. 4,224,948. The device combines a wristwatch and optical probing of tissue of the wrist to achieve a multi-functional device operable for displaying the wearer's heart rate.
Typically, a watch body or watch case is a few centimeters in width and has flat top and bottom portions. The case may have a thickness typically between 3 and 10 millimeters. It is generally constructed of rigid material such as molded plastics or composites. It may alternatively be made of metallic material having been molded or stamped. In most configurations, a watch case has a simple and symmetrically shaped periphery such as the circle illustrated in figure one of the disclosure.
A watch band may be connected to opposite sides of a watch body and may be used to affix the case to the wrist on its top or outer surface. The watch band is generally flexible and may be made from material such as cloth or plastic. Alternatively, watch bands may be made from durable metal material which has been formed into a chain of a plurality of link elements. A watch band portion attached at either side of a watch case forms means for affixing the watch about the wrist of a user. In this way, the timepiece may be worn as jewelry while simultaneously providing functionality.
A watch is preferably located on the top of the wrist as the arm is pronate. A watch worn about the wrist tends to naturally slide to the part of the wrist where the diameter is smallest. Since a watch band is typically wore with a bit of slack for comfort, the watch is meant to fit rather loosely about the wrist. Although the watch may tend to slide rotatably about the wrist, the watch case will stay on the top portion of the wrist unless the watch band is exceptionally loose. The watch is therefore located in a position which is easy to reference in a user's simple glance.
While exercising, and in particular in running sports, a watch may tend to move about the wrist in a manner which is undesirable. A runner's arms may be thrust alternately upward and downward in an effort to balance the motion of other body parts. This movement tends to cause a watch to become dislocated from its normal rest position and to move about the wrist in an oscillating fashion which may tend to annoy. Still further, the oscillating watch having a solid case of considerable mass may repeatedly hit or otherwise come into contact with the wrist bone in a manner which could cause pain. Of course, a natural response would be to tighten the watchband so that the watch fits tighter to the wrist and thus the motion of the watch case would be reduced. However, a tightened wrist band tends to reduce circulation and may otherwise be uncomfortable. Accordingly, runners and other athletes may elect to not wear a wristwatch during the practice of their athletics.
The problem of undesired movement during exercise is particularly troublesome to specialty devices which have been integrated with wristwatch type timepieces. For example, wristwatches configured to include devices which measure the wearer's heart rate. For example, consider U.S. Pat. No. 4,224,948 where Cramer et al, have devised a way for optical transducers on the bottom of a wristwatch to be coupled to the skin of the wearer. Although the device may work well when a user is sitting still, a watch which moves excessively tends to disturb the coupling of the transducers and the tissue being probed.
Indeed the inventor of the present invention was motivated by the device disclosed as U.S. Patent application having a Ser. No. 09/030,654, which also has a particular optical element which may suffer in performance when a watch is moved about the wrist excessively.